Thermosetting elastomer compositions primarily comprising a polymer having at least two alkenyl radicals in a molecule and a perfluoropolyether structure in its backbone cure into elastomers having good properties of heat resistance, chemical resistance, solvent resistance and water resistance. At the same time, these compositions are good in parting properties and thus, regrettably difficult to bond. JP-A 9-95615 and JP-A 2002-105319 describe such elastomer compositions to which various compounds having an alkoxysilyl radical, epoxy radical, carboxyl radical or acid anhydride residue are internally added as adhesive aids for tailoring the compositions so as to be adherent to metals, glass, ceramics and plastics. The addition of some adhesive aids, however, has negative impact that the mechanical strength of rubber lowers or the compression set declines.
In order to bond the elastomer compositions to various substrates at no sacrifice of such physical properties, a primer must be used rather than the internal addition of adhesive aids.
Commercially available primers include a silane primer based on a silane coupling agent, a primer based on synthetic rubber, a primer based on an acrylic resin, a primer based on a urethane resin, and a primer based on an epoxy resin.
These primers fail to achieve a satisfactory bond since they have low affinity to the above-referred thermosetting elastomer compositions and are less wettable at the interface.